Pulverizing and classifying machine



Jan. 8, 1946. H. G. LYKKEN ET AL 2,392,331

PULVERIZING AND CLASSIFYING MACHINE Filed Nov. 27, 1940 3 Sheets-Sheet 1INVENTORS. HENRY G. LYKKEN TTORNEY FIG. 3

Jan. 8, 19 46.

H. G. LYKKEN ET AL 2,392,331

PULVERIZING AND CLASSIFYING MACHINE INVENTORS. HENRY 6- LYKKEN ATTORNEYJan. 8, 1946. G. LYKKEN ET AL 2,392,331

7 PULVERIZING-.AND CLASSIFYING MACHINE Filed Nov. 27, 1940 5Sheets-Sheet 3 Fla. 4

INVENTORS. HENRY 6- LYKKEN Arron/v55 Patented Jam-8, 1946 UNITED STATESPATENT orr cs PULVERIZING AND CLASSIFYING Macrame Henry G. Lykken andWilliam H. Lykken,

Minneapolis, Minn.

Application November 27, 1940, Serial ni 337,314

Y 8 Claims. (01. 241-56) The present invention relates to mechanisms forpulverizing and classifying friable materials.

In pulverizing material by the interaction 01' particles of materialsuspended in air andmoved in a vortex, as, for example, in the patent ofHenry G. Lykken No. 1,838,560, issued December 29, 1931, or of hisPatent No. 1,768,621, issued 'July 1, 1930, pulverization of thematerial to a greater degree than necessary is to be avoided because (1)such is not an efficient use of the power used to operate the machine,(2) an undesired quantity of superfines are produced in the finishedproduct, and the superfines also interfere with the pulverization ofover-size material by acting as a cushion between the interactingparticles in the vortex. The same considerations are true, to a more orless extent, in other types of pulverizing equipment. At the same timeit is important that the classification ofthe pulverized material besuch that no over-size material escapes from the machine. In otherwords, it is desirable that the material delivered from the machine beas near a uniform size as possible, so that as soon as the materialattains the selected particle size it should be gotten out of themachineas soon as possible.

It is also important from a commercial standpoint that the maximumquantity of finished material be delivered so that a given machine willhave a maximum capacity per unit of power, or unit of time. Again, froma commercial standpoint, it is desirable that the same basic mechanismbe useable for a wide variety of materials and of particle sizes, suchas delivered material of 100 or 200 screen mesh or of 5 microns or less,or other selected sizes, with only slight and readily made changes foreither the different materials or the different particle sizes.

In our application Serial No. 285,484, filed July 20, 1939, which hasmatured into Patent No. 2,362,142 granted Nov. 7, 1944, there isdisclosed a machine in which pulverization and classifica-' tion of thepulverized material is done in a single chamber or a single pulverizingand classifying vortex. The vortex creating element in that case is abladed rotor. In the top of the casing, above the rotor chamber, is afan or discharge chamber into which the finished material is delivered,but the outlet or communication between the rotor and fan chambers isaxial or around the shaft of the rotor. In the application of Henry G.Lykken, Serial No. 337,742, filed May 29, 1940, which has matured intoPatent No. 2,329,208 granted Sept. 14, 1943, certain improvements aredisclosed, particularly in connection with the arrangement of the bladesof the rotor to obtain greater eificiency in the pulverization andparticularly in the classification of the material in the rotor orvortex chamber. Here again the outlet from the rotor chamber is at thecenter of the machine. The machines disclosed in those applications arein successful commercial use, but apparently a recirculation of theoutgoingmaterial occurs in and around the axial inlet which retardsdischarge of the material from the vortex zone, and also results in someexcess of superfines. The present machine is an improvement over themachines of these applications, and eliminates such recirculation asoccurred therein, but

r retains the features of the changeable tapered rotor contour forcontrol of discharged particle size, the taper being between 12 eitherside of the vertical.

While the improvements are shown as applied to a mechanism of the typedisclosed in the afore- I said applications, the principles thereof areapplicable to classifiers which are separate from pulverizingmechanisms, or which are combined with other types of pulverizingmechanisms than the air vogex type. However, the improvements increase eefficiency of the pulverizing mechanism as well as the classification ofthe pulverized material.

Briefly, in the machine of .the present application the outlet from therotor chamber is an annular or ring-shaped slot-like opening, with thecentral and outer portions. of the outlet end of the vortex chamberclosed. By this arrangement the material which is pulverized in thevortex around the rotor does not have to enter the rotor to so great anextent to reach the outlet, as in the cases 01 the structures in saidapplications,

so that the finished material passes through the machine at a fasterrate, and a substantially less volume of superfines are produced.However, the

materi al does enter the rotor far enough, that the particles aresubjected to the centrifugal forces thereof to eject the over-sizeparticles, forcing them to the wall of the casing where they return tothe pulverizing vortex for a further reduction in size. Again, by havingthe outlet adjacent the edge of the rotor, or at an intermediate portionof the vortex, there is a more efiicient use of the air immediatelycarrying the sufliciently reduced material directly to the outlet fromall parts of the annular pulverizing vortex. I

In the machines of the prior applications and patents, fineness ofdelivered particle size is controlled in several ways, as by the speedof the rotor or vortex, the number and construction of the rotor blades,where used, the area of the axial outlet opening, and the volume of airpassing through the machine. With the present arrangement, other factorsare introduced for the control of delivered particle size, viz., th izeand the radial position of the annular outlet opening; although itshould be noted that either of these factors may vary also for materialsof different specific gravity which have the same particle size. Theseotherfactors may be substituted for the other variable controls, or theymay b used in conjunction with some or all thereof, with the advantageof the prompt and uninterrupted discharge cf the finished material.

Other advantages of the principles of our invention will be apparent tothose skilled in this field from this specification and the accompanyingdrawings in which there is disclosed, by way of example, the best modesof applying those principles which are now known to us. In the drawingsFigure 1 is a vertical section of a pulverizing and classifying machine;

Fig. 2 is a horizontal section, on the line 2--2 of Fig. 1, parts beingomitted to facilitate the illustration;

Fig. 3 is a vertical section of a pulverizing and classifying machineshowing a modification of the mechanism of Fig. 1; and

Fig. 4 is a vertical section of a classifier attach- -ment embodying theprinciples of our invention.

Referring to Fig. 1 of the drawings, a cylindrical casing II is mountedupon a bas l2, and is closed at its upper end by a recessed cover [3which has a discharge outlet l4 at one side thereof through whichfinished material is delivered to a collector system or a place of use,as may be desired. A shaft I5 is rotatably mounted in bearings l6 and I!carried by the cover l3 and base l2, respectively. The shaft [5 carriesat its lower end a pulley l8 which is connected by belts l9 to a drivepulley M on the shaft of an electric motor 22, which is also mountedupon the base Secured to the shaft intermediate its ends is a hub 23 ofa rotor which also comprises a base all as mor fully explained in theaforesaid application Serial No. 337,742. That is to say, theblade-plates 26 may have the same radial depth from top to bottom orthey may be tapered inwardly or outwardly particularly in the upperportions thereof. With an upwardly and outwardly tapered contour of theblade-plate shown in Fig. 1 the machine will successfully pulverizesugar and classify the same to a particle size of approximately tenmicrons.

Spaced below the bottom plate 24 of the rotor the casing has aring-shaped, dished bottom member 26 closing the rotor or vortex chamberat th bottom, and on the lower surface of the plate 24 are a pluralityof fan blades 29, the lower edges of which conform to the dished shapeof the bottom member 29, the blades extending to the edge of the rotorplate 24. Air is admitted to the casing through the opening 3|, passingupwardly through the central opening 32 of the bottom member 23, and isejected by the fan blades 29 into the casing II in the annular spacearound the rotor. The size of the air inlet 32 is controlled by a pairof plates, one of which is shown at 33, operating in guides 33A on thebottom member 28.

The upper end of the rotor is closed for a portion of its diameter by acircular disc 34 which fits upon the shaft i5 and extends radiallyoutwardly therefrom. This disc 34 is removable to be readilyinterchangeable for purposes hereinafter explained. Supported betweenthe casing II and cover I3 is a ring-shaped diaphragm 35 which ismounted'in substantial alignment h'orizontally with the disc 34 andextends radially inwardly toward the same with an annular outlet opening36 between the disc 34 and diaphragm shaft l5 and th rotor and fan. Thesame key may or may not be extended into the hub of the rotor. Fanblades 39 are carried by a ring-shaped plate 4| which is secured to theflange 42 of the hub 31. The fan blades 39 may be of any desired shapeor number and according to our experience to date may or may not overlapthe annular outlet opening 36 although theoretically it is desirable totaper the heels of the blades 39 toward the wall of the casing so thatth same terminates at the lower ends at least partially over the outletopening 36.

In order to replace the disc 34 and diaphragm 35, the bolts 43 boltingtogether the flanges of the cover 13 and easing H are removed permittingthe cover l3 with the bearing l6 to be lifted off the machine, whichthen exposes the fan. The fan is lifted off the shaft l5 whereupon thedisc 34 and the diaphragm 35, or either of them, may be lifted out andreplaced with other sizes of disc and diaphragm. This will be done whenit is desired to vary the size of the annular outlet opening 36 or itsradial location, or both. Thereupon will be re-inserted in place, andthe cover l3 and bearing l5 willbe replaced, and the parts againconnected together including the connection between the machine outletl4 and the apparatus to which it leads.

Material to be pulverized is fed to the casing ll through the opening 45by means of a feed screw 46 from a hopper 41, the screw being driven bya motor 48 through a reduction gearing 43, sprockets 5| and chain 52. Inthis way there is be regulated feed of material, and the rate of feedmay be changed by changing one or both of the sprockets 5 I. The feedopening 45 is located above the pulverizing zone and the feed isdirectly into the annular pulverizing vortex setup by the rotor in thelower portion of the rotor chamber. This lower portion of the chambermay be provided with a corrugated or ribbed lining 53, which isremovable, as shown, and will increase the differential movement betweenthe layers of air suspended material in the pulverizing vortex.

I In operation, air is admitted to the pulverizing and classifyingchamber through the opening 32,

' interactions.

2,892,881 and the motoris set into operation to rotate the rotor athigii speed to set up a vortex of air'in the annular zone around therotor. The rotor being of the closed end time, this vortex will'bemaintained in that space. Material is fed into the pulverizing vortexthrough the opening 45, at a rate such that the material to bepulverized will be maintained suspended in the'vortex so that violentinteraction of the particles upon each other is, setup as they moveabout in the vortex under the centrifugal forces acting upon them,

which will cause reductions in particle size. As the particles arereduced in size, they will seek new locations in the vortex. setting upfurther The. pulverized material will move upwardly in the rotor chambertoward the outlet 38.. Since the diaphragm '35 covers the ani nularvortex zone, the pulverized material will enter the rotor part way inits progress toward the annular outlet, whereby the'particles will besubiected to the additional centrifugal action of the rotor blades. Thisaction is proportioned so as to eject the oversize particles to theouter wall of the from one-half to two-thirds the diameter of the rotorand the annular outlet opening will vary between one and two andone-half inches in width, With a rotor rtwenty-two'inches in diameter atthe bottom, the rotor disc 34 may be either thirteen or fourteen inchesin diameter. 111' coarser pulverizing, this variation does not seem tomake much diiference. With this disc a diaphragm 35 having a centralopening of eighteen inches may be used so that the annular outletopening 36 will have a width of two or two and one-half inches. Whenmaterial such as sugar having a size to pass a 350 screen mesh(approximately thirty-five microns) the diaphragm in this constructionmay have a center opening of seventeeninches, thus reducing the width ofthe annular outlet 36 to one and one-half inches, and moving theeffective outlet toward the center of the machine. For finer material,of say five or ten micron size, the center opening of the diaphragm 35may be sixteen inches leaving an annular outlet one inch invwidth.

In the foregoing examples, the central disc 34 has remained the samediameter and the width of the outlet was varied by changing the width ofthe diaphragm but this is by no means a fixed practice. For example,with a light, flaky material the disc 34 will be smaller in diameter andentire vortex zone, the sufiiciently pulverized material will be free toget out of the machine immediately and continuously so that thepulverizing vortex is cleared of those particles with the production ofa minimum of superfines. Such 'superfines as may be produced will, underthe centrifugal action of the rotor, enter the rotor if any, will notinterfere with the pulverization taking place in the lower portion ofthe chamber. The rotation of the disc 34 at the center of the rotor willaid in removal of any superfines, but this disc need not rotate but maybe integral with the diaphragm 35 being joined thereto by small webs(not shown).

The action may also be described that during the converging of thepulverized material toward the annular outlet 36, the material will beconstantly subjected to the transverse centrifugal forces of the rotorblades so that over-size particles are kept from entering the outlet 36.As soon as the pulverized material passes through the outlet 36 itimmediately expands into the air currents produced'by the fan blades 39and will be discharged from the machine without further reduction insize.

It is difiicult to set down any definite rules for fixing either thesize of the annular outlet opening 36 or its radial position, whichmatters 34 and diaphragm 35, because the specific gravity of thematerial as Well as its other characteristics such a whether theparticles being removed from the rotor or vortex chamber are flat andflaky or substantially round must be taken into consideration also.However, a few examples determined from past experience with machinesconstructed according to our invention will'sufllce to guide thosewishing to duplicate this'inventio and apply the principles thereof.

. Generally speaking, the rotor disc 34 will be to the edge of therotor. 35

are determined by the relative sizes of the disc at the same time thenarrow outlet opening will be used so that the outlet is nearer to theaxis of the rotor. While with heavier, non-flaky material, the sameparticle size will be delivered from the machine with the outlet openingnearer In general, with any given material, the finer the particlev sizedesired, the nearer to the axis will the outlet 36 be located, and thenarrower will be that opening, and contrary-wise, the coarser theparticle size desired the nearer the edge of the rotor will be theoutletopening and the wider it will be. It should be observed that decreasingthe size of the opening or locating the same nearer the rotor axisdecreases the output capacity of the machine. The size of the openingwill be determined by the particle 'size desired and its location willbe chosen to afford maximum capacity, taking into consideration thenature of the material being worked upon.

Referring now to Fig. 3 in which a modified form of mechanism is shown,the construction and operation of the casing and cover, air inlet,material feed, rotor drive and mounting are the same as in connectionwith Fig. 1, as will be apparent from a comparison thereof, so that thesame need not be described in detail. Where like parts in the twoconstructions are referred to in connection with Fig. 3, they will beprefixed with the numeral 3.

In Fig. 3, the central portions of the rotor blades 325 are cut away atthe top thereof, as indicated at BI, and the hub of the rotor is cutaway a corresponding amount. Seated in the cut away portions of theblades is a disc 62 which fits upon the shaft 3|5. The hub- 331 of thefan is lengthened, as by the addition of a collar, to rest upon the topof the disc 62, and the key 338 is likewise extended so as to engage ina key-way in the discto rotate the same with the shaft 3 IS. Aring-shaped diaphragm 63 is supported with one edge between the casing3H and the cover 3l3 as shown, and the rotor blades 325, with theattached rotor blade plates 326, operate close to the diaphragm 63. Inthis case the diaphragm 63 is of greater radial extent than in Fig. 1,and in fact overlaps the outer edge of the disc 62, but

be subjected toa centrifugal action both aboveand below the disc 62, asan added precaution against over-size particles getting out of the ma- 1chine with the desired material.

Here again, the size of the annular outlet opening 64 may be varied insize and radial location, and the extent of the overlap between thediaphragm 63 and the disc 62, may be varied, according to the particlesize wanted and the nature of the material, but following in general theprinciples set forth above. With the inwardly tapered rotor plates,etc., shown in this figure the average delivered particle size will beabout 200 screen mesh, according to present experience. Theseadjustments will usually be made in the factory of the manufacturer ofthe-pulverizing apparatus, whereas in the construction of Figs. 1 and 2,the disc 34 and diaphragm 35, as well as the discharge fan and the rotorblade plates 26, may be changed either at the factory orby the customerfor use with different materials or ,for variations in deliveredparticle size.

Fig. 4 illustrates :the principles of-our invention applied to aclassifier attachment for pulverizing machines. It comprises a casing 1|having an open mouth 12 which may serve both as the inlet for thepulverized material and as the outlet for the rejected over-sizematerial flowing in opposite directions. Extendinginto the casing fromthe top thereof is a shaft 13 on the lower end of which is a rotorcomprising a hub, on the shaft, a bottom disc 15 and a plurality ofradial blades 16. A recessed cover 11 rests upon the casing H and has aring-shaped bottom plate 18 which extends radially inwardly so as tooverlie the edges of the rotor blades, and the rotor blades operate inproximity thereto.

Mounted upon the shaft 13 is a disc 19 which is in substantiallyhorizontal alignment with the bottom plate 18 of thecover but is spacedtherefrom so as to form an annular outlet 8i. The recessed cover IT hasa discharge fan mounted therein comprising a hub 82 which fits upon theshaft 13 and rests upon the top of the disc 19, the two being rotatedwith the shaft by means of a key 83. The flange of the hub 82 hasmounted upon it a ring-shaped plate 84 which carries the fan blades 84.An outlet 85 from the fan chamber provides a discharge port to thepulverized material to a collection system or a place of use, as thecase may be. Over the cover I1 is a support 86 for the upper bearing 81for the shaft 13, the shaft also having a lower bearing 88. The shaft isrotated from any suitable source of power indicated by the pulley 89 andbelts 9|.

As will be understood, the classiflerwill operate in the same manner asdescribed in connection with the machine of Fig. 1, namely, the fanblades 84 will draw air and the suspended material through the casing Hwhere it will be acted upon by the rotor 16 to set up a classifyingvortex which will reject the over-size material and allow the materialof the proper size to pass through the annular outlet BI and from thencethrough the outlet 85. The bottom plate 18 and the disc 19 may be of anyselected sizes so as to either vary the size of the annular outlet 8| orthe radial location thereof. Also, the blades of the rotor may have anyselected outer contour as, for example, tapered, as indicated by thedotted lines 92.

Other modifications may be made in the arrangement and location of partswithin the spirit and scope of our invention, and such modiflca tionsare intended to be covered by the appended claims.

We claim:

1. In a pulverizing and classifying machine, a casing, means for feedingair and material to said casing, a vertical shaft rotatably mounted insaid casing-a bladed rotor of less diameter than said casing and mountedon said shaft, 0.

disc of less diameter than the rotor and mounted upon the shaft adjacentthe upper end of the rotor so as to partly close the spaces between saidblades, the disc being approximately onehalf the diameter of the rotor,a diaphragm mounted upon the casing and extending radially inwardtherefrom in position to form with said v disc a narrow annular outletforair and material acted upon by said rotor, a fan mounted upon {.saidshaft on the opposite side of said outlet from portion of the upper endof said rotor so as said rotor, an outlet from the casing in the areawhere said fan is mounted, and means for driv-' ing said shaft.

2. In a pulverizing and classifying machine, a casing, means for feedingair and material to said casing, a vertical shaft rotatably mounted insaid casing, a bladed rotor of less diameter than said casing andmounted on said shaft, a disc of less diameter than the rotor andmounted upon the shaft adjacent the upper end of the rotor, so as topartly close the spaces between said blades, the disc beingapproximately one-half the diameter of the rotor, a diaphragm mountedupon the casing and extending radially inward therefrom in position toform with said disc a narrow annular outlet for air and material actedupon by said rotor, and means for driving said shaft.

3. In a pulverizing and classifying machine, a casing having an airinlet at one end thereof and a material and air outlet at the other endthereof, said casing also having a rotor chamber, a

bladed rotor of less diameter than said chamber and mounted therein, therotor being arranged to set up a pulverizing vortex of air and suspendedmaterial in the space around said rotor, means for feeding into saidvortex at a regulated rate material that is to be pulverized, meansclosing the spaces between the blades of said rotor at one end, a discpartly closing the spaces between the blades of the rotor at the otherend thereof and rotatable therewith, the disc constituting part of anend closure for the rotor chamber, a diaphragm also partly closing therotor chamber and spaced from said disc to form therewith an annularoutlet from the rotor chamber for the sufficiently pulverized material,and means for driving said rotor.

4. In a pulverizing and classifying machine, a casing, means for feedingair and material to said casing, a bladed rotor of less diameter thanthe casing and mounted vertically for rotation therein to set up avortex of air and material in said casing, a disc mounted at the centralto be readily removable and replaceable, a diaphragm mounted at the sameend of said rotor as said disc so as to be readily removable andreplaceable and cooperating with the disc to form an annular outlet fromthe portion of the casing in which the rotor is mounted, the disc anddiarotor being cut away at the upper end thereof,

a radial disc mounted upon said shaft in the cut-away portions of saidrotor and partly closing the spaces between said rotor blades, adiaphragm mounted upon said casing and extending radially inward closeto the uncut-away portions of said blades and into the vicinity of saiddisc to form a narrow annular outlet therewith, and means for drivingsaid shaft.

6. In a pulverizing and classifying machine, a casing, means for feedingair and material to said casing, a vertical shaft rotatably mounted insaid casing, a radially bladed rotor of less diameter than said casingand mounted on said shaft, the rotor setting up and maintaining apulverizing vortex of air and suspended material and the outer edges ofsaid blades being tapered upwardly to govern the fineness of theparticle size of pulverized material delivered from the machine, meansadjacent the upper end of said rotor providing an annular outlet for thesufliciently pulverized material, the radial position of the annularoutlet of said opening being in the region between one-half andtwo-thirds of the diameter of the rotor and being chosen in accordancewith the taper of said rotor blades, a fan for inducing a current of airin the space between the rotor and casing and through said annularoutlet, and means for driving said shaft.

7, In a pulverizing and classifying machine, a

casing, means for feeding air and material to said casing, a verticalshaft rotatably mounted in said casing, a radially bladed rotor of lessdiameter than said casing and. mounted on said shaft, the rotor settingup and maintaining a pulverizing vortex of air and suspended materialand the outer edges of said blades being tapered upwardly to govern thefineness of the particle size of pulverized material delivered from themachine, means adjacent the upper end of said rotor providing an annularoutlet for the 'sufilciently pulverized material, the size of theannular outlet of said opening being between-one and two and one-halfinches and being chosen in accordance with the taper of said rotorblades, a fan for inducing a current of air in the space between therotor and casing and through said annular outlet, and means for drivingsaid shaft.

8. In a pulverizing and classifying machine, a casing, means for feedingair and material to said casing, a vertical shaft rotatably mounted insaid casing, a radially bladed rotor of less diameter than said casingand mounted on said shaft, the rotor setting up and maintaining apulverizing vortex of air and suspended material and the outer edges ofsaid blades being tapered inwardly and upwardly in an area between l2either side of the vertical, means adjacent the upper end of saidrotor'providing'an annular outlet for the sufliciently pulverizedmaterial, the

radial position of the' annular outlet being in an area between one-halfand two-thirds of the diameter of the rotor, and the width of theannular opening being between one and two and one-half inches, a fanforinducing a current of air in the space between the rotor and casingand through said annular outlet, and means for driv- 1 ing said shaft.

HENRY G. LYKKEN. WILLIAM H, LYKKEN.

